Back to EveryPatent.com
United States Patent |
5,296,937
|
Nakatani
,   et al.
|
March 22, 1994
|
Image processing apparatus using recursive filters
Abstract
In a diagnostic X-ray apparatus, an image signal output from a TV camera
connected to an image intensifier tube is supplied to a noise reducer
through an A/D converter. The noise reducer comprises a first recursive
filter for adding a value which is (1-a) times the input to the noise
reducer and a value which is a times an output of the first recursive
filter (a factor a is fixed to a value close to 1), a second recursive
filter for adding a value which is (1-k) times the output of said
fluoroscopy means and a value which is k times the output of the first
recursive filter, a subtracter for subtracting the output of the second
recursive filter from the input to the noise filter for every pixel, and a
factor table for setting the factor k of the second recursive filter in
accordance with the difference obtained by the subtracter such that the
factor k and the difference have an inverse proportional relationship if
the difference has a positive value.
Inventors:
|
Nakatani; Yoshinori (Ootawara, JP);
Honda; Michitaka (Yaita, JP)
|
Assignee:
|
Kabushiki Kaisha Toshiba (Kawasaki, JP)
|
Appl. No.:
|
883389 |
Filed:
|
May 15, 1992 |
Foreign Application Priority Data
Current U.S. Class: |
358/448; 378/98.12 |
Intern'l Class: |
H05G 001/64 |
Field of Search: |
358/448,443,447,463,166,167,111
382/56
|
References Cited
U.S. Patent Documents
4677478 | Jun., 1987 | Kruger et al. | 358/111.
|
5016104 | May., 1991 | Lim | 358/463.
|
5018179 | May., 1991 | Kaneko | 358/111.
|
5051842 | Sep., 1991 | Shimazaki | 358/463.
|
Primary Examiner: Brinich; Stephen
Attorney, Agent or Firm: Oblon, Spivak, McClelland, Maier & Neustadt
Claims
What is claimed is:
1. An image processing apparatus comprising:
first recursive filter means for adding a present image and a last image
with predetermined weights to output an image in which a motion portion is
blurred;
second recursive filter means for adding the present image and the output
of said first recursive filter means with weights to output an image in
which a noise is reduced; and
means for determining the weights of said second recursive filter means for
every pixel in accordance with a difference between a pixel value of the
present image and the pixel value of the last image.
2. An apparatus according to claim 1, wherein said weight determining means
comprises means for determining the weights of said second recursive
filter means in accordance with a difference between a pixel value of the
present image and the pixel value of the output of said first recursive
filter means.
3. An apparatus according to claim 1, wherein said weight determining means
comprises means for determining the weights of said second recursive
filter means in accordance with a difference between a pixel value of the
present image and the pixel value of the output of said second recursive
filter means.
4. An apparatus according to claim 1, wherein said weight determining means
comprises means for selecting one of the outputs from said first recursive
filter means and said second recursive filter means and means for
determining the weights of said second recursive filter means in
accordance with a difference between a pixel value of the present image
and the pixel value of the image output from said selecting means.
5. An apparatus according to claim 1, wherein said weight determining means
comprises means for setting the weight of said second recursive filter
means for the present image to a large value if the difference has a
positive large value and a negative value and the weight of said second
recursive filter means for the output of said first recursive filter means
to a large value if the difference has a positive small value.
6. An apparatus according to claim 1, wherein said weight determining means
comprises a first low-pass filter for smoothing the present image and
compares the present image output from said first low-pass filter and the
last image to produce a difference.
7. An apparatus according to claim 6, wherein said weight determining means
further comprises a second low-pass filter for smoothing the last image
and compares the present image output from said first low-pass filter and
the last image output from said second low-pass filter to produce a
difference.
8. An apparatus according to claim 1, wherein said first recursive filter
means adds the present image and the last image with the same weight.
9. An apparatus according to claim 1, wherein said second recursive filter
means comprises means for selecting one of the outputs of said first
recursive filter means and said second recursive filter means and means
for adding the present image and the output of said selector means with
weights to reduce the noise in the present image.
10. A diagnostic X-ray apparatus comprising:
fluoroscopy means for outputting a fluoroscopic image signal by picking up
a fluoroscopic image obtained by radiating an X-ray to an object;
first recursive filter means including a frame memory, for adding an output
of said fluoroscopy means and an output of said frame memory with
predetermined weights to write the result of addition into said frame
memory;
subtracter means for subtracting the output of said frame memory from the
output of said fluoroscopy means for every pixel;
means for generating a factor k in accordance with the difference obtained
by said subtracter means, the factor k and the difference having an
inverse proportional relationship if the difference has a positive value;
and
second recursive filter means for adding a value which is (1-k) times the
output of said fluoroscopy means and a value which is k times the output
of said first recursive filter means.
11. An apparatus according to claim 10, wherein said factor generating
means generates the factor k having a given value when the difference is
smaller than a first positive predetermined value, the factor k having a
value of 0 when the difference is larger than a second positive
predetermined value which is larger than the first predetermined value,
and the factor k having a value gradually decreasing from the given value
to 0 when the difference is within a range between the first and second
predetermined values.
12. An apparatus according to claim 11, wherein the factor k has a value
which is linearly decreased from the given value to 0 when the difference
is within the range between the first and second predetermined values.
13. An apparatus according to claim 11, wherein the factor k has a value
which is decreased in a quadratic curve manner from 0.5 to 0 when the
difference is within the range between the first and second predetermined
values.
14. A diagnostic X-ray apparatus comprising:
fluoroscopy means for outputting a fluoroscopic image signal by picking up
a fluoroscopic image obtained by radiating an X-ray to an object;
first recursive filter means including a frame memory, for adding an output
of said fluoroscopy means and an output of said frame memory with
predetermined weights to write the result of addition into said frame
memory;
second recursive filter means for adding a value which is (1-k) times the
output of said fluoroscopy means and a value which is k times the output
of said first recursive filter means, a factor k being a positive number
between 0 and 1;
subtracter means for subtracting the output of said second recursive filter
means from the output of said fluoroscopy means for every pixel; and
means for setting the factor k in accordance with the difference obtained
by said subtracter means, the factor k and the difference having an
inverse proportional relationship if the difference has a positive value.
15. An apparatus according to claim 14, wherein said factor setting means
sets the factor k having a given value when the difference is smaller than
a first positive predetermined value, the factor k having a value of 0
when the difference is larger than a second positive predetermined value
which is larger than the first predetermined value, and the factor k
having a value gradually decreasing from the given value to 0 when the
difference is within a range between the first and second predetermined
values.
16. An apparatus according to claim 15, wherein the factor k has a value
which is linearly decreased from the given value to 0 when the difference
is within the range between the first and second predetermined values.
17. An apparatus according to claim 15, wherein the factor k has a value
which is decreased in a quadratic curve manner from the given value to 0
when the difference is within the range between the first and second
predetermined values.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image processing apparatus for reducing
random noises of an image by using a recursive filter.
2. Description of the Related Art
A recursive filter represented as follows is known as one example of noise
reducers for reducing the random noises of a digital image.
Y.sub.i =a.multidot.Y.sub.i-1 +(1-a).multidot.X.sub.i ( 1)
where Y.sub.i is a filtered output of a present frame, Y.sub.i-1 is a
filtered output of the last frame, X.sub.i is a live image (an input to
the filter) of the present frame, and a is a filter factor.
Thus, the recursive filter reduces the random noise by adding the product
of the live image X.sub.i and the filter factor a to the product of the
filtered output image Y.sub.i-1 of the last frame and the filter factor
(1-a), i.e., by averaging the present image and the last image.
In such a recursive filter, the filter factor a is changed within a range
between 0 and 1. If the filter factor a approaches to 0, a weight of the
last image approaches to 0 and a weight of the present image approaches to
1. Thus, the influence of the filter is decreased and it can be said that
a weak filter is applied to the image. On the contrary, if the filter
factor a approaches to 1, the weight of the last image approaches to 1 and
the weight of the present image approaches to 0. Thus, the influence of
the filter is increased and it can be said that a strong filter is applied
to the image. The more the filter factor a appropriates to 1, the more the
images are averaged with respect to time and the more the random noises
can be reduced.
However, if an image includes an object which is moving and this motion
portion of the image is applied with the strong filter having the filter
factor a close to 1, the residual image of the last frame appears on the
present image or the locus of the moving object appears on the present
image. Therefore, the contrast of the image is lowered and the artifact is
generated so that the quality of the image is degraded.
For example, in a diagnostic X-ray apparatus for displaying a fluoroscopic
image obtained by radiating an X-ray to the patient, if a catheter, a
guide wire, and the like are moved in a blood vessel to perform a recovery
operation of a constricted portion of the blood vessel and the strong
filter having the filter factor a close to 1 is applied to the image, the
image of the distal end of the catheter or the guide wire will be obscured
by the residual image, resulting in inconvenience in diagnosis.
In order to solve this drawback, there is provided an apparatus in which a
movement of the object is detected and the recursive filter processing for
every pixel is selectively performed based on the result of detection,
i.e., the recursive filter processing is performed only for the still
portion and is not for the motion portion. One example of such an
apparatus is disclosed in Published Unexamined Japanese Utility Model
Application (PUJUMA) No. 63-55400. FIG. 1 shows a block diagram of this
prior art.
An image signal from an image pick-up device (not shown) is supplied to an
analog-to-digital converter 1. In the case of the diagnostic X-ray
apparatus, a TV camera to which a fluoroscopic X-ray image is incident
from an image intensifier tube outputs the image signal. The image signal
of every frame is converted to a digital image signal X.sub.i. The output
of the A/D converter 1 is multiplied with a factor (1-a) by a multiplier
2. The filter factor a is changed within a range between 0 and 1. The
output of the multiplier 2 is supplied to a first input terminal of an
adder 3. A filtered output Y.sub.i-1 of the last frame, i.e., (i-1)th
frame from a frame memory 4 is supplied to a second input terminal of the
adder 3 through a multiplier 5. The multiplier 5 multiplies the input
signal Y.sub.i-1 with the filter factor a.
An output of the adder 3 (=(1-a) X.sub.i +a.multidot.Yi-1) is supplied to a
first terminal I1 of a selector 6. The output of the A/D converter 1 is
supplied to a second terminal I2 of the selector 6. The selector 6 selects
one of the input signals I1 and I2 based on an output of a comparator 7.
The comparator 7 compares the output of the A/D converter 1 with the
output of the frame memory 4 for every pixel to obtain the difference
between them. The selector 6 outputs the input Il to perform the filter
processing when the difference is smaller than a threshold level and the
input 12 not to perform the filter processing when the difference is not
smaller than the threshold level. The output of the frame memory 4 is
output through a digital-to-analog converter 8 to be displayed on a
monitor device (not shown).
In this conventional apparatus, the movement of the object is detected
based on the difference between the pixel value of the live image X.sub.i
output from the A/D converter 1 and the pixel value of the last filtered
image Y.sub.i-1 from the frame memory 4. When the movement is detected,
the selector 6 is caused to select the input 12 to write the input live
image X.sub.i into the frame memory without performing the filter
processing. Since the filter processing is performed only for the still
portion, it is possible to apply a strong filter in which the filter
factor a is set to a large value, e.g., 0.8 or 0.9.
However, the filtered pixels and non-filtered pixels are adjacent to each
other at the boundary between the motion portion and the still portion.
This boundary markedly appears on the filtered image so that the image
becomes unnatural. For example, if there is a motion portion surrounded by
a still portion, the still portion is averaged and the pixel values
thereof somewhat change but the motion portion is not filtered and the
pixel values thereof do not change. Therefore, there is a large difference
between the pixel value in the motion portion and that in the still
portion, thereby giving an unnatural feeling.
In addition, the threshold value for determining whether or not the filter
processing is performed is difficult to properly set. If the threshold
level is set too small, the number of pixels subjected to the filter
processing is decreased and the influence of filtering is reduced.
Therefore, the random noises are hardly reduced. If it is set too large,
the number of pixels subjected to the filter processing is increased and
the influence of filtering is increased. Therefore, the motion portion is
blurred.
As described, in the conventional recursive filter which selectively
performs the filter processing for every pixel using the threshold value,
it is not possible to satisfy the contradictory requirements of the
recursive filter which are to reduce the random noises by averaging the
images and to prevent the degradation of the quality of the image due to a
lowering of the contrast of the image and a generation of the artifact.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an image
processing apparatus using a recursive filter which can reduce random
noises of the image without degrading the quality of the image.
According to one aspect of the present invention, there is provided an
image processing apparatus comprising first recursive filter means for
adding a present image and a last image with predetermined weights to
output an image in which a motion portion is blurred, second recursive
filter means for adding the present image and the output of the first
recursive filter means with weights to output an image in which a noise is
reduced, and means for determining the weights of the second recursive
filter means for every pixel in accordance with a difference between a
pixel value of the present image and the pixel value of the last image.
According to the image processing apparatus of the present invention, the
first recursive filter means outputs a filtered image in which the motion
portion is blurred and the noises are reduced. The second recursive filter
means performs a strong filter processing for the still portion for
reducing noises but the motion portion is not filtered. The motion portion
of the present image is output from the second recursive filter means as
it is and thus is not blurred.
Additional objects and advantages of the present invention will be set
forth in the description which follows, and in part will be obvious from
the description, or may be learned by practice of the present invention.
The objects and advantages of the present invention may be realized and
obtained by means of the instrumentalities and combinations particularly
pointed out in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated in and constitute a part
of the specification, illustrate presently preferred embodiments of the
present invention and, together with the general description given above
and the detailed description of the preferred embodiments given below,
serve to explain the principles of the present invention in which:
FIG. 1 is a block diagram of a conventional recursive filter;
FIG. 2 is a block diagram of an overall diagnostic X-ray apparatus having a
first embodiment of a noise reducer according to the present invention;
FIG. 3 is a block diagram of the noise reducer according to the first
embodiment of the present invention;
FIG. 4 shows an example of the contents of a factor table of the first
embodiment;
FIG. 5 shows another example of the contents of the factor table of the
first embodiment;
FIG. 6 shows a still another example of the contents of a factor table of
the first embodiment;
FIG. 7 shows a process in which the random noises are reduced according to
the first embodiment;
FIG. 8 is a block diagram of the noise reducer according to a second
embodiment of the present invention;
FIG. 9 shows a process in which the random noises are reduced according to
the second embodiment;
FIG. 10 is a block diagram of the noise reducer according to a third
embodiment of the present invention; and
FIG. 11 is a block diagram of the noise reducer according to a fourth
embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A preferred embodiment of an image processing apparatus according to the
present invention will now be described with reference to the accompanying
drawings. A diagnostic X-ray apparatus is described as an embodiment of
the present invention.
FIG. 2 is an overall block diagram of the diagnostic X-ray apparatus. An
X-ray emitted from an X-ray tube 12 supported by a supporting mechanism
(not shown) is incident on an image intensifier tube 18 which is also
supported by the supporting mechanism through a patient 16 lying on the
top plate 14 of a bed 14. Thus, a fluoroscopic image is output from the
image intensifier tube 18. A TV camera 20 picks up the fluoroscopic image.
An output image signal is supplied through an analog-to-digital converter
22 to a noise reducer 24 formed of a recursive filter. An output of the
noise reducer 24 is supplied to a display device 28 through a
digital-to-analog converter 26.
The details of the noise reducer 24 is shown in FIG. 3. The noise reducer
24 is mainly formed of two recursive filters 32 and 34, two frame memories
36 and 60, a factor table 38, and a subtracter 40. A live image signal
X.sub.i of the present frame output from the A/D converter 22 is supplied
to the recursive filters 32 and 34 and a first input terminal (+) of the
subtracter 40.
The recursive filter 32 is formed of multipliers 42 and 44, and an adder
46. The multiplication factors of the multipliers 42 and 44 are (1-a) and
a. The filter factor a can be changed within a range between 0 and 1.
Here, the factor a is fixed to a value close to 1. Therefore, the
recursive filter 32 applies the same strong filter to all the pixels. That
is, the multiplier 42 multiplies the live image X.sub.i with the factor
(1-a) and the multiplier 44 multiplies the output W.sub.i-1 of the frame
memory 36 with the factor a. The output of the multiplier 42 is added to
the output of the multiplier 44 by the adder 52 and the output of the
adder 46 is written into the frame memory 36 as a first filtered image
W.sub.i. An output W.sub.i-1 of the frame memory 36 is an image of the
last filtered image and is supplied to the first and second recursive
filters 32 and 34.
The output Y.sub.i of the second recursive filter 34 is supplied to a frame
memory 60 whose output Y.sub.i-1 of the last frame is supplied to a second
terminal (-) of the subtracter 40. The subtracter 40 subtracts the second
filtered image Y.sub.i-1 from the live image X.sub.i and supplies the
difference to the factor table 38. The factor table 38 stores the factor k
for the various differences as a table and supplies the factors (1-k) and
k to multipliers 48 and 50 of the second recursive filter 34 in response
to the output from the subtracter 40.
The factor k is changed within a range between 0 and 1. The example of the
factor table is shown in FIG. 4. In this example, the factor k is fixed to
a given value C, e.g., 0.5 if the difference is smaller than a first
predetermined value A (a positive value), fixed to 0 if the difference is
larger than a second predetermined value B which is larger than the value
A, and gradually decreased from 0.5 to 0 if the difference is within the
range between the values A and B. Therefore, the still portion having the
small difference and a portion which is included in the last image but not
in the present image are strongly filtered in which the present image and
the last image are averaged, thereby reducing the noises of the still
portion and the portion which is included in the last image but not in the
present image. On the contrary, the motion portion in the present image is
subjected to the filter processing of a grade according to the degree of
the movement, i.e., the less strong filter processing is applied to the
more motion portion.
It is possible to modify the contents of the factor table as shown in FIGS.
5 and 6. In FIG. 5, the factor k is changed like a quadratic curve near
the upper threshold value B. The influence of the filter is more gradually
reduced near the upper threshold value B so that the unnatural feeling of
the image in the portion having the difference of the upper threshold
value B. In FIG. 6, the factor k is changed like a quadratic curve near
both the lower and the upper threshold values A and B. The influence of
the filter is more gradually reduced near both the lower and the upper
threshold values A and B so that the unnatural feeling of the image in the
portions having the differences of the lower and the upper threshold
values A and B.
In the second recursive filter 34, the multiplier 48 multiplies the live
image X.sub.i of the present frame with the factor (1-k) and the
multiplier 50 multiplies the second filtered image W.sub.i-1 of the last
frame output from the frame memory 36 with the factor k. The output of the
multiplier 48 is added to the output of the multiplier 50 by the adder 52
and the output of the adder 52 is output to the D/A converter 26 as the
noise reduced image Y.sub.i and is written into the frame memory 60.
The operation of the first embodiment will be described. A motion image
signal of thirty frames per one second output from the TV camera 20 is
supplied to the noise reducer 24 through the A/D converter 22. In the
noise reducer 24, the first recursive filter 32 outputs the following
filtered image W.sub.i.
W.sub.i =(1-a).multidot.X.sub.i +a.multidot.W.sub.i-1 (2)
As described above, the factor a is set to near 1 so that the output
W.sub.i of the first filter 32 has been subjected to the strong filter
processing. In the filtered image W.sub.i, the random noises are reduced
but the motion portion is blurred. The second recursive filter 34 outputs
the following filtered image Y.sub.i.
Y.sub.i =(1-k).multidot.X.sub.i +k.multidot.W.sub.i-1 (3)
As described above, the factor k for every pixel is a variable in
accordance with the difference output from the subtracter 40 and is set to
0.1 to 0 if the large movement is detected. If the factor k is set to
these small values, it can be regarded that the filter is not applied to
the image since the influence of the last image output from the first
recursive filter 32 does not appear on the present image. In this case,
though the random noises are not reduced, it is prevented that the image
of the motion portion is blurred due to the strong filtering processing.
If the movement is hardly detected, the factor k is set to a large value,
for example, 0.5. If the factor k is set to the large value, the last
image and the present image are averaged and the random noises can be
reduced.
A process in which the random noises are reduced according to the present
embodiment is described with reference to FIG. 7. FIG. 7 shows the change
of the fluoroscopic image caused by the insertion of the catheter during
the recovery operation of a constricted portion of the blood vessel.
The first recursive filter 32 performs a strong filter processing and the
first filtered image W.sub.i-1 is output. In the first filtered image
W.sub.i-1, the random noises are reduced and the motion portion (encircled
portion M in FIG. 7) is blurred. The motion portion M includes a new image
N which is included in the present image but is not in the last image and
an old image O which is included in the last image but is not in the
present image. The subtracter 40 detects the motion portion M by
subtracting the filtered image Y.sub.i-1 of the last frame from the line
image X.sub.i of the present frame. Therefore, the new image N has a
positive value and the old image O has a negative value. The factor table
produces the factor k having a large value to perform a strong filter
processing for the old image 0 and a still portion other than the portion
M and the factor k having a small value not to perform a filter processing
for the new image N. The random noises for the old image 0 is greatly
reduced compared to the case in which the present image is output as it
is. As a result, the random noises for the still portion are greatly
reduced and the motion portion is not blurred in the filtered image
Y.sub.i.
According to the present embodiment, only the new image in the motion
portion is output as it is and the other portion is strongly filtered in
the second recursive filter 34 so that the random noises in the still
portion are greatly reduced and the blurring of the motion portion is
prevented.
Other embodiments of the present invention will be described below. FIG. 8
is a block diagram of a second embodiment. The second embodiment differs
from the first embodiment only in that the subtracter 40 obtains the
difference between the live image X.sub.i and the first filtered image
W.sub.i-1. In the first embodiment, a preferable result is obtained for a
moving object such as a heart. However, a following drawback is predicted
for the still portion such as a head. In the image of the head, only the
image of the catheter or the guide wire is moved It is assumed that the
catheter starts moving at (i-1)th frame and is moved linearly as shown in
FIG. 9. There is no trouble up to the calculation of Y.sub.i. In the
calculation of Y.sub.i+1, the subtracter 40 detects a motion portion M1.
However, there is a still portion S1 of only the upper quarter in the
first filtered image W.sub.i. The motion portion M1 is separated from the
still portion S1 in the second filtered image Y.sub.i+1 since the portion
between the motion portion M1 and the still portion S1 is mostly affected
by the first filtered image W.sub.i. If the motion portion is detected by
the subtracter 40 based on the difference between the live image X.sub.i
and the first filtered image W.sub.i-1, as shown in FIG. 8, it is possible
to overcome this drawback. Therefore, it is desirable to use the first
embodiment for the motion object such as a heart and the second embodiment
for the still object such as a head.
FIG. 10 is a block diagram of a third embodiment of the present invention.
The third embodiment is a combination of the first and second embodiments
using selectors 62 and 64. One of the output of the frame memory 36 and
the output of the frame memory 60 is selected by the selector 62 and
selected image is supplied to the subtracter 38. The selector 62 is
manually switched and is caused to select the output of the frame memory
36 for the head and to select the output of the frame memory 60 for the
heart.
Further, one of the output of the frame memory 36 and the output of the
frame memory 60 is selected by the selector 64 and selected image is
supplied to the multiplier 50 of the recursive filter 34. The selector 64
is manually switched independent of the selector 62.
FIG. 11 is a block diagram of a fourth embodiment of the present invention.
The fourth embodiment is an improvement of the third embodiment to which
low-pass filters 66 and 68 are added. The low-pass filters 66 and 68 are
connected to the input terminals of the subtracter 40. The live image
X.sub.i is supplied to the subtracter 40 through the low-pass filter 66
and the output of the selector 62 is supplied to the subtracter 40 through
the low-pass filter 68. The low-pass filters 66 and 68 smooths the images
so that the accuracy of the motion detection is improved since the present
image and the last image are compared to each other after the noises are
reduced. It is possible to omit the low-pass filter 68 for the last image
since the last image has already passed the recursive filters 32 or 34.
As has been described above, according to the present invention, since the
motion portion is blurred and the random noise is reduced by the first
filter, the new image which is included in the present image but is not in
the last image is not filtered by the second filter, and only the still
portion is strongly filtered by the second filter, it is possible to
provide an image processing apparatus using a recursive filter which can
reduce random noises of the image without degrading the quality of the
image.
Additional advantages and modifications will readily occur to those skilled
in the art. Therefore, the present invention in its broader aspects is not
limited to the specific details, representative devices, and illustrated
examples shown and described herein. Accordingly, various modifications
may be made without departing from the spirit or scope of the general
inventive concept as defined by the appended claims and their equivalents.
For example, the present invention is not limited to use for processing
medical images but can be applied to use for processing any type of image,
wherein an effective result is obtained.
Top